Header and separable tubular unit



Oct. 2, 1934. w H ARMACOST 1,975,494

HEADER AND SEPARABLE TUBULAR UNIT Filed July 7. 1952 INVEN R W; I b M H. X wm ATTORNEY Patented Oct. 2, 1934 UNITED STATES 1,975,494 HEADER AND SEPARABLE TUBULAR UNIT -Wilbur H. Armaecst, New York, N. Y., assignor to The Superheater Company,

New York,

' Application July 7, 1932, Serial No. 621,218

1 Claim.

My invention relates to arrangements for releasably securing the ends of tubular units to headers and aims to provide an arrangement adapted to minimize the tendency to leakage at 6 the joints between the headers and units.

It is an object of my invention also to provide an arrangement whereby the ligaments in headers between adjacent seats for removable units may be increased for a given fluid pressure and dis- 10 tance between centers of the seats for the units.

The novel features of my invention are pointed outin the appended claim. The invention itself, however, together with its objects and advantages, will best be understood from the following detailed description of twoforms of apparatus in accordance with my invention, both selected from a number of possible embodiments thereof. In

.20 and portions of tubular heater units associated therewith.

Fig. 2 is a sectional view at right angles to Fig. 1. Fig. 3 is a plan view on a reduced scale of the header shown in Figs. 1 and 2, the units and bolts being removed.

Fig. 4 is a plan view of a modified form of a header within my invention.

In an arrangement in wide use for steam heaters and like heating apparatuses, a header is as-- sociated with a number of tubular heating units, the apertures in the header for registering with the ends of the units being arranged in a row longitudinally of the header and in an axial plane thereof and bolts being placed between each pair of apertures for exerting a thrust on the center of a clamp having its ends engaging a pair of units. Such an arrangement has met with very considerable success in practice, but it is found that, at the temperatures and pressures advo- 49 cated for many installations at present, difliculties are encountered in preventing leakage between the headers and the ends of the units. I have concluded from a study of a number of actual installations that the principal cause of 4,5 such leakage is due to inequality in the thermal expansion between the tubular fluid carrying units and the bolts. In order that the joints may be tight when the steam, or other high pressure fluid to be heated, is first turned into the header, the

- 50 nuts on the bolts must be set up tight when cold.

being heated, whereas the metal of the bolts, due

to air cooling, is at a considerably lower temperature. The difference in thermal expansion between the units and the bolts at such times may increase the stress on the bolts sufficiently to strain them beyond their elastic limits. If the [SQ bolts are so unduly strained, leakage at the joints is almost sure to occur. In accordance with my invention, the stress on the bolts due to unequal thermal expansion is reduced by half.

In the arrangement shown for'this purpose in Figures 1, 2, and 3, 10 is a header of the eccentric type having an axis 11, and a row of apertures 12, 12 arranged longitudinally therein and each adapted to register with one end of the hole in a tubular heating unit 14. At the upper'end of each aperture 12 is a seat 16 against which the end or" a unit 14 is forced to make a fluid tight joint. Preferably the surface of header 10 is machined oif as shown at 1'7 so that seats 16, are all countersunk into a plane surface. For forcing the end of the unit 14 against its cooperating seat 16, I have illustrated an arrangement similar in some respects to that in ordinary use and comprising a collar 18 on each unit 14 and surrounding such unit near the end adjacent header 10. Each unit 14 is enlarged as shown at 20 so as to form a bearing for the corresponding collar 18. For applying thrust against each collar 18, I have shown a clamp 22 having a central aperture 24 for receiving a bolt 26 which threads into a radial hole 27 in the header 10 at the line of greatest metal thickness on the cross-section of such header. Instead, however, of using one bolt for two units, as in the ordinary arrangement, and having the units 14 and bolts 26 in the same plane, the bolts 26 are placed radially with the header 10 in a plane including the axis of such header while the units 14 are placed in a plane at one side of said plane so that the axis of each unit 14 and registering aperture 12 therefore, instead of being radial, forms a cord of the header 10. The plane or planes of the units 14 should be, however, parallel to the plane of the bolts 26. One end of each clamp 22 bears on a collar 18 whereas the other end of each clamp 22 is supported from the header 10 by a means at substantially the same temperature as the bolts 26. In the arrangement shown, such means includes a post 28, the top of which contacts with the underface of one end of a clamp 22. The other end of each post 28 rests on a flat 30 on the header 10. It will be seen that header 10 is of the eccentric type having both its inner and outer surfaces generally cylindrical, but the inner surface not concentric with the outer surface.

Such type of header, while not novel with me,

promotes the objects I have in mind by providing a relatively thick section in which the flats 1'7 and 30 can be made by casting or by machining the header in a planer or milling machine to form notches in the outer surface of header 10 or which flats 17 and 30 form sides. The flats are, moreover, one on each side of the row of bolts 26 and such bolts are placed along the line of the thickest section of the wall or" the header 10 as shown. While I have shown posts 28 as separate, they may be part of clamps 22. As shown, eachfpost rests on flat 30 and each post and its associated bolt determines a plane at right angles to the axis of header 10, but I do not limit myself to this. Nuts 32 are applied at the ends of bolt 26 for contacting with clamps 22 at points midway between their ends so as to force the clamps against the posts 28 and collars 18 and thereby exert thrusts against units 14 to force them tightly against their seats. Posts 28 being out of contact withrthe fluid to be heated, such as flows thru the units 14, have substantially the temperature of the bolts 26 and do not expand at any greater rates than such bolts so that the stress against the bolts 25, due to greater temperature or" the units 14 is only one-half what it would be if both ends of clamps 22 were arranged to thrust against units 14. However, I do not limit myself to this;

It Will be seen that the arrangement described for the seats, bolts, and clamping means permits applicant to obtain the object set forth above of limiting the stress on the bolts due to thermal expansion of the units at the same time that he is able to maintain the close spacing of the units 14 longitudinally of the header 10 required by commercial considerations.

The arrangement of Fig. 4 differs from that of Figs. 1 2, and 3 only in that the apertures 12, 12 are 'spaced twice as far apart as shown in Fig. 3 and another row 13, 13 of apertures for registering with units 14 is placed on the opposite side of the plane of bolt holes 27 from the apertures 12. In such an arrangement the plane surfaces 17 and 17' for the seats 16 serve as seats for the posts 28.

In addition to the advantages of my invention, mentioned above, it Will be noticed that thinner headers may be employed for the same pressure than those required by the ordinary arrangement due to the fact that the apertures 12 are set as cords of the header 10 so that there is a greater thickness of metal parallel to the axis of the aperture 12 than if such aperture were radial and also because the metal for the bolt holes 27 is not removed from the ligament of the apertures 12. i

What I claim is: i

The combination of a header having cylindrical inner and outer surfaces eccentric to each other, a row of bolts threaded into said header along itsiine of maximum wall thickness, said header having notches on each side or" said row providing fiat surfaces lying at right angles to said bolts and having apertures and seats for units in at least one of said flat surfaces, tubular units cooperating with said seats, and clamping means individual to each unit resting at one end on one of said surfaces and including a lever a an angle to the axis of the header.

WILBUR H. ARMACOST. n 

